The roles of sex hormones as modulators of lung function and disease have received significant attention as differential sex responses to various lung insults have been recently reported. The present study utilized a bleomycin-induced pulmonary fibrosis model in C57BL/6 mice to examine potential sex differences in physiological and pathological outcomes. Endpoints measured included invasive lung function assessment, immunological response, lung collagen deposition, and a quantitative histological analysis of pulmonary fibrosis. Male mice had significantly higher basal static lung compliance than female mice (p < 0.05) and a more pronounced decline in static compliance following bleomycin administration when expressed as overall change or percentage of baseline change (p < 0.05). In contrast, there were no significant differences between the sexes in immune cell infiltration into the lung or in total lung collagen content post-bleomycin. Total lung histopathology scores measured using the Ashcroft method did not differ between the sexes while a quantitative histopathology scoring system designed to determine where within the lung the fibrosis occurred indicated a tendency towards more fibrosis immediately adjacent to airways in bleomycin-treated male vs. female mice. Furthermore, castrated male mice exhibited a female-like response to bleomycin while female mice given exogenous androgen exhibited a male-like response. These data indicate that androgens play an exacerbating role in decreased lung function following bleomycin administration, and traditional measures of fibrosis may miss critical differences in lung function between the sexes. Gender differences should be carefully considered when designing and interpreting experimental models of pulmonary fibrosis in mice.